This invention relates to a compact, high power continuously variable power divider network or system for Radio Frequency (xe2x80x9cRFxe2x80x9d), microwave, or other high energy electromagnetic treatment systems (microwave).
High Power microwave and radio frequency networks are used to provide energy for heating, curing, sterilizing, cooking, medical imaging, medical therapy, plasma generating, and other processing of substrates or treated media. The goal for such processing is to optimize the process. This processing can include multiple locations for a single generator, thus requiring some sort of power division. This typically means utilizing the minimum amount of energy to completely process two or more substrates from a single electromagnetic source in an efficient manner while, at the same time, greatly enhancing the quality and yield of the final product. The applications are primarily high power microwave and/or radio frequency energy utilization including the engineered wood industry, the food service industry, medical applications, heating and processing of manufactured products such as composite material production, the hydrogenation of petroleum products for octane boosting, plasma systems for the electronics industry as well as others.
In a typical device, an electromagnetic generator is located at a differing location in respect to a waveguide from its load. The waveguide itself can have a rectangular, circular, or other cross section, the section of which is dependent on the system design and desired mode or electromagnetic field map within the system, network or component.
Power division and/or power divider networks and systems are used to split portions of high energy signals that are supplied by the electromagnetic generators for application to several different parts, portions or locations within a system using electromagnetic energy for processing, depending on the requirements of the process. Depending on the specific requirements of the process, the power division ratios are or need to be set and/or adjusted according to these requirements. The power divider itself is selected in consideration of the waveguide and mode.
In the power divider networks of prior design, the power division ratio is permanently set by mechanically positioning an inductive and/or capacitive structure in the network such that the impedances of each of the multiple output ports, as seen from the perspective of the electrical center of the network, achieve the desired power division ratio. The power division ratios would thus be set permanently during the manufacturing process. This design has the disadvantage that, once it is set (typically in the measurement laboratory), the power division ratio can not be easily altered. This is especially so during operation of the device. Indeed, one of the only practical methods of altering or adjusting the power division ratio(s) is to actually physically remove the junction power divider network from a system where the power division ratio is a necessary parameter, and installing a completely new and different power divider with a different power division ratio.
In the present invention, the division ratio is adjusted by selectively variable capacitance probes located in respect to one of two or more outputs and a single input 13. Preferably, a capacitance probe is utilized in each output (two disclosed). The probes accomplish the power division by the resistance they create, with a larger resistance lowering the power through its respective output. The preferred impedance distribution and matching post (impedance post) 14 facilitates the power division by providing a matching balancing function as later described. The adjustment of the preferred two probes 25, 26 further preferably are made simultaneously from an initial division ratio at initial design positioning through a differing division ratio range. This maintains overall efficiency while allowing for differing power outputs. Also, by synergistically altering the sizing and location of the various components, the respective power division ratio can be modified (for example by modifying one probe""s diameter or the divider post""s position). Further, other factors such as mode, aspect, etc. can also be modified (for example using an applicator on one of three outputs or having only two of three outputs adjustable). Other modifications are also possible without deviating from the invention as claimed herein.
Microwave and RF processing can be used in a large variety of applications, some of which have been described above. This particular invention covers a new, simple, cost effective implementation of an electromagnetic network that can tolerate extremely high power electromagnetic field levels that are commonly required in industrial and scientific microwave and RF systems while, at the same time, provide a means, under manual, motorized or motorized-automatic control, to selectively adjust the power division ratio between the output ports of the network, while at the same time, maintaining a low voltage standing wave ratio (xe2x80x9cVSWRxe2x80x9d) presented at the input port of the invention. The need to adjust or vary this power division ratio frequently accompanies many radio frequency or microwave process.
It is an object of this invention to simplify power division waveguides;
It is another object of this invention to reduce power reflection in power division devices;
It is a further object of this invention to optimize power transfer in division networks;
It is an object of this invention to increase the efficiency of processes that require differing ranges of power division ratio(s);
It is another object of this invention to provide a means of adjusting the network, while microwave or radio frequency power is being applied, to provide equal, or unequal power division ratios;
It is a further object of this invention to provide a means of adjusting the power division ratio between two output ports so as to allow a higher output microwave or RF power from one output port, and a lower microwave or RF power from the other output port to be adjusted in a manner that is required for an RF heating or processing system so as to add this control parameter and make it available to controllers of the overall process;
Other objects and a more complete understanding of the invention may be had by referring to the following drawings in which: